Sewing mechanism of sewing machine



Feb. 17, 1959 TOSHIO TATEISHI 2,873,706

SEWING MECHANISM OF SEWING MACHINE 4 Sheets-Sheet 1 lZwGIZ/TOJ Filed Jan. 23, 1956 T Ta; 236 bah/r) Feb. 17, 1959 TOSHIO TATEISHI SEWING MECHANISM OF SEWING MACHINE 4 Sheets-Sheet 2 Filed Jan. 23, 1956 me a-2:01 T fatal/k520i,

Feb. 17, 1959 TOSHIO TATEISHI 2, 7

' SEWING MECHANISM OF SEWING MACHINE Filed Jan. 25, 1956 4 Sheets-Sheet 3 Feb. 17, 1959 TOSHIO TATEISHI 2,873,706

SEWING MECHANISM OF SEWING MACHINE Filed Jan. 23, 1956 4 Sheets-Sheet 4 lNVENTORx United States Patent 2 Claims. (Cl. 112-181) This: invention relates to a loop-taker for sewing machines.

When rearward sewing operations are, carried, out, in

theconventional lock stitch sewing machine,- both the upper needle thread and the lower bobbinthread are pulled rearward somewhat even though the rotary element. of the loop-taker is in the same position as in forward sewing operations so that the needlemoves up and down. at a position behind the lower bobbin thread. Accordingly, the lower thread interlinks with the needle thread loop through action of a looping: member, with resulting so-called knots as, are shown in Figure 17.

An important object of this invention isv to provide a. sewing mechanism whereby the. above noted disadvan-v tage. is overcome.

Another object of. this inventionisto, provide. a sewing mechanism capable of carrying: out.v the same needle and looper thread concatenations in both forward and backward sewing operations.

With thev foregoing. and other objects in view, this invention consists inthe details of construction of sewing mechanism to be hereinafter morev fully set forth and claimed.

In descri-bing'this invention in detail, an example of, this invention will 'be' described in connection with the. accompanying" drawings, wherein like characters denote corresponding parts in the several views, and in which:

Fig. 1 is a vertical sectional view showing the operative position of the loop-taker involving the invention.

lfig. 2 is an enlarged front view of the improved loopta er.

Fig. 3 is a sectional view along the line 3-3 in Fig. 2. Fig. 4 is a plan view of the loop-taker shown in Fig. 2.

Fig. 5 is a front view showing the relation between the loop-taker and a plate supporting a stationary ring of the said loop-taker.

Fig. 6 is a plan view of the said plate shown in Fig. 5.

Fig. 7 is a rear view of the said plate shown in Fig. 5.

Figs. 8, 9, 12, 13, 14 and 15 are front views of the improved loop-taker partly in section and disclosing successive operative phases thereof.

Fig. 10 is a plan view of the loop-taker as observed in the direction of arrows 1010 on Figure 8.

Fig. 11 is a plan view of the loop-taker as observed in the direction of arrows 11 on Figure 9.

Fig. 16 is a view showing a seam which is formed by usual sewing devices in the forward sewing operation.

Fig. 17 is a view showing a seam which is formed by usual sewing devices in the backward sewing operation.

Referring to Fig. 1, a rotary cup-shaped member 5 is fixed to the outer end of the lower shaft 4 by screws 7 at its securing arm 6 which is formed integral with the said cup-shaped member, the said shaft 4 being located under the bed 1 and rotated alternatively clockwise and counter-clockwise 180 rotation thereof by means of a forked crank 3 which is driven by a vertical rod 2. The said cup-shaped member 5 is, as clearly shown in Fig. 3,

2,873,706 Patented Feb. 17, 1959 "ice fitted in the; rear inside. of a rotary ring 8 and then fixed therewith by several screws 9. In the front inside of the said ring 8 is loosely engaged a stationary ring 10 which, in turn is supported by a hook-shaped ring edge 11 formed on the front of the said ring 8.

A bar-shaped projection 12 is provided on the front center of the upper portion of the stationary ring 10-, as shown in Fig. 2, and a supporting. plate 13 is fixed to the stationary portion (not shown) by screws 14, 14 so as to cover the upper half of the rotary ring 8 so that a slight space may be formed between said plate 13 and ring 8' as shown in Fig. 5. On the rear surface of the said plate 13 are laterally fixed two holding pieces 15' and 15,-by-screws16. The free ends 17, 17 of thesaid holdingpieces are turned rearward so as to hold the said projection 12 of the stationary ring 10-between them so that the stationary ring 10 may not rotate even when the rotary ring 8 is rotated so that the said stationary ring 10 alwaystakes a constant position.

As shown in Fig.2, the projection 12 is equipped with an angularly projecting piece 18 at the leftside thereof so that-the distance between the said piece 18 and the rotary ring 8 may be-as small as possible, the said piece 18 being provided with a'slanted thread mouth 19. The lower thread coming from. the bobbin 20 fitted in the stationary ring 10 is put into the said mouth 19 through a cutout 21. v p

The rotary ring 8 is provided with a sharp-pointed hooking piece 22 along the: circumference thereof and on the outer surface of the said ring 8 is fixed a ringshaped guide plate 23. The said plate 23 is provided with a bobbin thread loop, deflecting cam 24 projecting inwardly so as to slightly cover the outer surface of the ring .8, and at both sides of the said cam, there being formed windows 25 and 26. The position of the said cam 24-is so selectedthat ittakes the uppermost position just prior to the end of the sewing needle reaching the outer surface of the rotary ring 3 during the needle lowering, stroke.

Operation of the sewing mechanism as described above will be described as follows.

In Figure 8 is shown the position of the loop-taker just after completion of one seam stitching. In this position, the upper thread A is held at the uppermost position and the loop deflecting cam 24 of the ringshaped guide plate 23 takes the uppermost position as shown in Figure 10, so that the lower thread B is pushed rearward by the said cam 24 so as to retreat to the position behind the needle 27 while receiving a suitable tension. The rotary ring 8 rotates for a further slight angle from the position in Figure 8 to the position in Figure 9 and then is reversed to rotate counter-clockwise, as shown in Figure 9 by arrow line. In the position shown in Figure 9, the needle 27 takes the lower position in front of the lower thread B, because the said thread B has been already pushed rearward by the cam 24. Soon after, with upward movement of the needle 27 from its lowest position, the upper thread A loosens and this loosened portion is caught up with the hooking piece 22 in the course of the above-mentioned counterclockwise rotation of the rotary ring 8, whereby the thread A is pulled downward, as shown in Figure 12. As clear from Figure 12, the thread A hooked with the hooking piece 22 passes through the rear side of the lower thread B, because the thread B has already gotten out of range of the cam 24 and takes the normal front position.

Thus, after a half counterclockwise rotation of the rotary ring 8, this ring reverses its rotation and takes the position as shown in Figure 13. In this position, the thread A is released by the booking piece 22 and is pulled up in the next position, as shown in Figure 14. In this pulling stroke, the thread A is pulled up along the periphery of the stationary ring 10, so that the pulled portion of the thread A forms a loop C, as shown in Figure 14. v I V When the mechanism takes the position of Figure 15, the sewing is completed and then returns to the position in Figure 8.

In the conventional mechanisms, the lower thread B enters into said loop C in case of backward sewing, whereby lock-stitching such as shown in Figure 17 is formed.

According to this invention, however, the lower thread B is retreated forcibly to the position behind the needle path by means of the convex loop deflecting cam in the needle lowering stroke, so that the lower thread B does not enter into said loop C even when the said loop is formed. Accordingly, the sewing mechanism of this invention can carry out eflectively the same lock-sewing in both the forward and backward sewing operation without forming knots.

In accordance with this invention, the thread mouth 19 for guiding the lower thread is located as close as possible to the rotary ring 8 and the mouth is located as far back as possible on the side of the projection 12 in such a manner that it almost comes in contact with the front surface of the rotatable ring 8, so that the lower thread is always shifted backward so as to promote the backward pushing action of the cam 24. Accordingly, in the forward stitching, as shown in Fig. 16, there is no apprehension that the lower thread returns frontward just after leaving the cam 24 and before the lowering stroke of the needle 27, so that the lower thread is located.at the position sufiicient for making lowering motion of the needle very easy. (Fig. 4).

As described above, according to this invention, very accurate lock-stitching can be accomplished in every instance of forward and backward sewing operations with the seams in each instance of the same thread concatenation.

It is obvious that changes may be made in the form and construction of the invention without departing from the basic principles thereof. It is not therefore desired to confine the invention to the exact forms herein shown 4 and described, but it is desired to include all forms which properly come within the scope of the appended claims.

I claim:

1. An oscillatory loop-taker for a sewing machine cooperating with a vertically reciprocable thread carrying needle comprising, an oscillatory shaft, a cup-shaped member having its closed side secured to one end of said shaft and projecting axially therefrom, a needle thread engaging hook mounted on said cup-shaped member, a bobbin supporting ring provided with a bobbin thread guide disposed adjacent the line of needle reciprocation, and a bobbin thread deflecting cam supported by said cup-shaped member which comprises a bobbin thread engaging surface opposed to the open side of said cupshaped member, said surface being convex toward the cup-shaped member, the highest point of said surface being disposed toward the cup-shaped member beyond the plane comprising the line of needle reciprocation and perpendicular to the axis of said shaft, and the move-v ment of said loop-taker being so synchronized with the needle reciprocation that the highest point of said cam surface is in uppermost position when the lower end of the needle is positioned between the uppermost position and the work resting surface of the machine at the downward stroke of the needle and operating to push the bobbin thread toward said cup-shaped member in order to move the needle in front of the bobbin thread.

2. The structure according to claim 1, wherein said bobbin thread deflecting cam is integral with a ringshaped guide plate surrounding and secured to said cupshaped member and the convex thread engaging surface being a convex edge portion of said last ring and which convex edge portion is symmetrical to a transverse center line of the cam which is parallel with the axis of said shaft.

References Cited in the file of this patent UNITED STATES PATENTS Hemleb Dec. 30, 1930 

